Imerys Pigments, Inc.

Ecc International Limited

Steven M Fortier

Robert J Pruett

Jun Yuan

Anthony V Lyons

David O Cummings

William L Garforth

Daniel John Panfil

Jose M Rodriguez

Ricardo Perez

Bruce Jackson

David P Bryan

Peter B O'Rorke

William B Jackson

Paper coating composition comprising an engineered kaolin pigment containing stacks and platelets of unground coarse particles where greater than 96% by weight is less than 5 microns, of which some kaolinite books or stacks are concentrated in the greater than 1 micron size fraction; 88% to 95% by weight is less than 2 microns; 65% to 85% by weight is less than 1 micron; and 15% to 25% by weight is less than 0.25 micron. A first embodiment comprises particles with a shape factor Ad between 7 and 9 which represents a significant number of stacks and some platelets. A second embodiment comprises particles with a shape factor of 11 or 12 which represents the presence of some stacks with a majority of platelets. The kaolin clay pigments form clay-water slurries of 69% solids or greater. As a coating, the composition gives a G. E. brightness between 88 and 94. The engineered pigment is processed so that the desired shape factor is met, which shape factor is equated to the aspect ratio or morphology of the pigment.

Engineered kaolin pigment composition for paper coating

Method for the production of precipitated calcium carbonate having a selected crystal form, products produced thereby and their uses

Fine-grained aragonite precipitated calcium carbonate is produced on a commercial scale by seeding with a coarse-grained aragonite precipitated calcium carbonate. The coarse-grained seeding material is produced by interrupting, after the production of 0.1 to 0.6 g/L min. of calcium carbonate, the supply of carbon dioxide to the quicklime slurry early in the reaction to allow subsequent nucleation of the crystals and then continuing the supply of carbon dioxide at reaction rates of 0.1 g/L min. to 0.6 g/L min. This coarse-grained seeding material has a Blaine surface area which may be less than 30,000 cm.sup.2 /g, the solids of which are 35 to 70 weight percent aragonite, and is added to subsequent batches as a slurry at about 1 weight percent, based on the total weight of the slurry of the material to be seeded. For the seeded batches, carbonation is carried out at reaction rates of up to 1.8 g/L min. at the commercial scale resulting in fine-grained aragonite product. This final seeded product need not be ground, has solids in which the weight percent of aragonite is greater than 90, has a median particle size between 0.30 to about 0.5 microns, a particle size distribution where about 60 to 70 weight percent are less than 0.5 micron equivalent spherical diameter, and a Blaine surface area which may be greater than 35,000 cm.sup.2 /g.

Seeding of aragonite calcium carbonate and the product thereof

Paper coating composition comprising an engineered kaolin pigment containing stacks and platelets of unground coarse particles where greater than 96% by weight is less than 5 microns, of which some kaolinite books or stacks are concentrated in the greater than 1 micron size fraction; 88% to 95% by weight is less than 2 microns; 65% to 85% by weight is less than 1 micron; and 15% to 25% by weight is less than 0.25 micron. A first embodiment comprises particles with a shape factor between 7 and 9 which represents a significant number of stacks and some platelets. A second embodiment comprises particles with a shape factor of 11 or 12 which represents the presence of some stacks with a majority of platelets. The kaolin clay pigments form clay-water slurries of 69% solids or greater. As a coating, the composition gives a G.E. brightness between 88 and 94. The engineered pigment is processed so that the desired shape factor is met, which shape factor is equated to the aspect ratio or morphology of the pigment.

A method for producing a high solids slurry of an acid-resistant precipitated calcium carbonate for shipping purposes is disclosed. A low solids of about 18 wt. % to 20 wt. % solids slurry is treated with a chemical additive, such as sodium aluminate, in order to impart acid resistance to the calcium carbonate, and is dewatered to form an intermediate solids slurry of about 44 wt. %. This intermediate solids slurry is then diluted with a fraction of the low solids slurry which was treated with the chemical additive, in order to bring the intermediate slurry to a final high solids slurry of about 35 wt. %. Acid is added to the final product slurry in order to reduce the pH of the final slurry to within a buffering range of about 7.0 to 6.5. The final product slurry of about 35 wt. % comprises an acid-resistant calcium carbonate composition with a pH of about 7.0 which can be shipped for ultimate use when making paper under neutral pH conditions. The final product slurry has a Brookfield viscosity ranging from 200 to 500 centipoise at 100 rpm.

Method for producing high solids aqueous acid-resistant calcium

Growing community of inventors

Milledgeville, GA, United States of America

Steven M Fortier